Display device and method of manufacturing the same

ABSTRACT

A display device includes a display unit including a plurality of pixels respectively including thin film transistors; and a terminal unit including an array of a plurality of terminals. The display device includes a first insulating film provided on a substrate; the thin film transistors provided on the first insulating film; a second insulating film that is provided in the display unit and in the terminal unit and has openings located between the plurality of terminals; a plurality of signal lines that are provided on the second insulating film and are respectively connected to the thin film transistors, and a plurality of terminal lines that are provided on the second insulating film in the terminal unit; and a third insulating film that is located on the plurality of signal lines and the plurality of terminal lines and is formed of an organic insulating film.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 14/608,036, filed on Jan. 28, 2015, which claims the benefit ofpriority from the Japanese Patent Application No. 2014-021746, filed on6 Feb. 2014, the entire contents of which are incorporated herein byreference.

FIELD

The present invention relates to a display device including a terminalunit that includes a plurality of terminals, and a method ofmanufacturing the same.

BACKGROUND

Recently, display devices that control display gray scale of each of aplurality of pixels by use of a thin film transistor (TFT), such asliquid crystal display devices, organic EL (electroluminescence) displaydevices and the like, have been developed. In such a display device,each of the plurality of the pixels that includes a thin film transistorneeds to be supplied with an electric current. For this purpose, thedisplay device includes a terminal unit including a plurality ofterminals that are connected to an external circuit or the like andreceive the electric current, and a wiring unit including a plurality oflines connected to the plurality of terminals. For such a displaydevice, it is an important issue to prevent deterioration of theterminal unit and the wiring unit to improve the reliability ofconnection at the terminal unit.

Conventionally in order to realize this, a technology is proposed bywhich a protrusion is formed in the display device by use of aninsulating film in a terminal unit on a substrate including TFTs and theprotrusion is used to provide the conduction between the terminal unitand a flexible wiring board (Japanese Laid-Open Patent Publication No.2008-065135). According to this technology, a thermosetting insulatingfilm is located between a conductive film for terminals that is formedon the protrusion and a bump formed on the flexible wiring board, andthe conductive film for terminals and the bump are put into contact witheach other via a hole formed in the insulating film, so that theconductance is provided.

However, in the above-described conventional display device, there maypossibly be a restriction on the position of the connection part becauseof the protrusion formed in the terminal unit and the bump formed on anexternal circuit (flexible wiring board). In this case, the reliabilityis provided by the insulating film, but the connection resistance mayundesirably be high. In addition, since a plurality of minuteprotrusions need to be formed, the load on the manufacturing process mayundesirably be high.

SUMMARY

A method of manufacturing a display device in an embodiment according tothe present invention is a method of manufacturing a display deviceincluding a display unit that includes a plurality of pixelsrespectively including thin film transistors, and a terminal unitincluding an array of a plurality of terminals, signals to control anoperation of the thin film transistors respectively being input into theplurality of terminals. The method includes forming a first insulatingfilm on a substrate; forming the thin film transistors on the firstinsulating film; forming a second insulating film in the display unitand in the terminal unit after the formation of the thin filmtransistors; forming, in the second insulating film, contact holes thateach expose at least a part of a corresponding thin film transistoramong the plurality of thin film transistors, while forming a pluralityof openings in the second insulating film in the terminal unit; forming,on the second insulating film, a plurality of signal lines respectivelyconnected to the thin film transistors via the contact holes, whileforming, on the second insulating film, a plurality of terminal lineswith the openings being located therebetween at the same time as theformation of the signal lines; and forming a third insulating film of anorganic insulating film on the plurality of signal lines and theplurality of terminal lines.

The method of manufacturing the display device may further includepartially removing the third insulating film in the terminal unit toexpose a part of each of the plurality of terminal lines; and forming aconductive film that covers the exposed parts of the plurality ofterminal lines.

A method of manufacturing a display device in another embodimentaccording to the present invention is a method of manufacturing adisplay device including a display unit that includes a plurality ofpixels respectively including thin film transistors, and a terminal unitincluding an array of a plurality of terminals, signals to control anoperation of the thin film transistors respectively being input into theplurality of terminals. The method includes forming a first insulatingfilm on a substrate; forming the thin film transistors on the firstinsulating film; forming a second insulating film in the display unitand in the terminal unit after the formation of the thin filmtransistors; forming, in the second insulating film, contact holes thateach expose at least a part of a corresponding thin film transistoramong the plurality of thin film transistors, while forming a pluralityof openings in the second insulating film in the terminal unit; forming,on the second insulating film, a plurality of signal lines respectivelyconnected to the thin film transistors via the contact holes, whileforming, on the second insulating film, a plurality of terminal lineswith the openings being located therebetween at the same time as theformation of the signal lines; forming a third insulating film of anorganic insulating film on the plurality of signal lines; forming afourth insulating film of an inorganic insulating film on the thirdinsulating film and the plurality of terminal lines; partially removingthe fourth insulating film in the terminal unit to expose a part of eachof the plurality of terminal lines; forming a conductive film thatcovers the exposed parts of the plurality of terminal lines; forming afifth insulating film of an organic insulating film on the conductivefilm; and partially removing the fifth insulating film to expose a partof the conductive film.

The conductive film may be formed of a light-transmissive conductivefilm.

The third insulating film may be formed of an acrylic resin orpolyimide.

A display device in an embodiment according to the present inventionincludes a display unit including a plurality of pixels respectivelyincluding thin film transistors, and a terminal unit including an arrayof a plurality of terminals, signals to control an operation of the thinfilm transistors respectively being input into the plurality ofterminals. The display device includes a first insulating film providedon a substrate; the thin film transistors provided on the firstinsulating film; a second insulating film that is provided in thedisplay unit and in the terminal unit and has openings located betweenthe terminals; a plurality of signal lines that are provided on thesecond insulating film and are respectively connected to the thin filmtransistors, and a plurality of terminal lines that are provided on thesecond insulating film in the terminal unit; and a third insulating filmthat is located on the plurality of signal lines and the plurality ofterminal lines and is formed of an organic insulating film.

The plurality of terminals may be respectively connected to theplurality of terminal lines via a plurality of contact holes provided inthe third insulating film.

A display device in another embodiment according to the presentinvention includes a display unit including a plurality of pixelsrespectively including thin film transistors, and a terminal unitincluding an array of a plurality of terminals, signals to control anoperation of the thin film transistors respectively being input into theplurality of terminals. The display device includes a first insulatingfilm provided on a substrate; the thin film transistors provided on thefirst insulating film; a second insulating film that is provided in thedisplay unit and in the terminal unit and has openings located betweenthe terminals; a plurality of signal lines that are provided on thesecond insulating film and are respectively connected to the thin filmtransistors, and a plurality of terminal lines that are provided on thesecond insulating film in the terminal unit; a third insulating filmthat is located on the plurality of signal lines and is formed of anorganic insulating film; a fourth insulating film that is formed of aninorganic insulating film located on the third insulating film and theplurality of terminal lines and has a plurality of contact holes thateach expose a part of a corresponding terminal line among the pluralityof terminal lines; the plurality of terminals provided on the fourthinsulating film and are respectively connected to the plurality ofterminal lines via the plurality of contact holes; and a fifthinsulating film provided on the plurality of terminals and exposes apart of each of the plurality of terminals.

The plurality of terminals may be formed of a light-transmissiveconductive film.

The third insulating film may contain an acrylic resin or polyimide.

BRIEF EXPLANATION OF DRAWINGS

FIG. 1 is a plan view showing a schematic structure of a display devicein an embodiment according to the present invention;

FIG. 2 is a vertical cross-sectional view showing a schematic structureof the display device in the embodiment according to the presentinvention;

FIG. 3A is a plan view of the display device in the embodiment accordingto the present invention;

FIG. 3B is a cross-sectional view of the display device in theembodiment according to the present invention;

FIG. 3C is an isometric view showing a schematic structure of thedisplay device in the embodiment according to the present invention;

FIG. 4 is a cross-sectional view showing a schematic structure of adisplay device in embodiment 1 according to the present invention;

FIG. 5A is a plan view of a terminal unit of the display device inembodiment 1 according to the present invention;

FIG. 5B is a cross-sectional view of the terminal unit of the displaydevice in embodiment 1 according to the present invention;

FIG. 6 is a cross-sectional view showing a schematic structure of awiring unit of the display device in embodiment 1 according to thepresent invention;

FIG. 7 is a cross-sectional view showing a schematic structure of adisplay device in embodiment 2 according to the present invention;

FIG. 8A is a plan view of a terminal unit of the display device inembodiment 2 according to the present invention;

FIG. 8B is a cross-sectional view of the terminal unit of the displaydevice in embodiment 2 according to the present invention;

FIG. 9 is a cross-sectional view showing a schematic structure of awiring unit of the display device in embodiment 2 according to thepresent invention; and

FIG. 10 is a cross-sectional view showing a schematic structure of aconventional display device.

DESCRIPTION OF EMBODIMENTS

The present invention has an object of solving the above-describedproblems and providing a display device that keeps a high yield ofmounting an external circuit and thus having a high reliability, and amethod of manufacturing such a display device. The present inventionalso has an object of realizing such a display device by a simplemanufacturing method without significantly changing an existingmanufacturing method.

Hereinafter, embodiments of a display device according to the presentinvention will be described with reference to the attached drawings. Thedisplay device according to the present invention is not limited to thefollowing embodiments, and may be carried out in any of variousmodifications.

FIG. 1 shows a schematic structure of a display device 10 in anembodiment according to the present invention. The display device 10 inthis embodiment includes a substrate 7, and also includes a display unit9 including a plurality of pixels 101, a driver IC 102, an externalcircuit 103 (ex. a flexible printed circuit), and a scanning drivingcircuit 104 that are provided on the substrate 7. The display unit 9includes a plurality of control signal lines g1-1 through g1-3 runningin a horizontal direction in FIG. 1, and a plurality of data signallines dl through d3 running in a vertical direction in FIG. 1. Thecontrol signal lines g1-1 through g1-3 and the data signal lines dlthrough d3 cross each other. At intersections of the control signallines g1-1 through g1-3 and the data signal lines dl through d3, theplurality of pixels 101 are located; namely, the plurality of pixels 101are located in a matrix.

In FIG. 1, three control signal lines g1-1 through g1-3 and one datasignal line dl are provided as crossing each other for one pixel 101.The present invention is not limited to such a structure. A line thatsupplies a certain voltage, such as a power supply line or the like, maybe included in the display unit 9. At each pixel 101, a pixel circuit isprovided. The pixel circuit includes a thin film transistor thatcontrols write of data voltages in accordance with control signalssupplied from the control signal lines g1-1 through g1-3 and thuscontrols light emission of the pixel 101; a capacitance element thatstores a data voltage supplied from a corresponding data signal lineamong the data signal lines dl through d3; and the like.

On the substrate 7, a plurality of line patterns are provided. Theplurality of line patterns supply power source voltages and drivingsignals to the driving circuit 104 and also are connected to the earth.In FIG. 1, the display device 10 includes one driving circuit 104.Alternatively, the display device 10 may include a plurality of drivingcircuits 104 in a peripheral area along the display unit 9. Ends of theplurality of line patterns are respectively connected to a plurality ofterminals provided on the substrate 7. The plurality of terminals areconnected to the external circuit 103 that supplies a driving power, adriving signal, a ground potential and the like from an external device.The external circuit 103 may be a flexible printed circuit (FPC).

Hereinafter, with reference to FIG. 2, FIG. 3A, FIG. 3B and FIG. 3C, thestructure of the display device 10 in this embodiment according to thepresent invention will be described in more detail. FIG. 2 is a verticalcross-sectional view showing the display device 10 in this embodimentaccording to the present invention. FIG. 3A is a plan view of thedisplay device 10, and FIG. 3B is a cross-sectional view of the displaydevice 10. FIG. 3C is an isometric view showing a schematic structure ofthe display device in this embodiment according to the presentinvention.

In the following, an organic EL display device including an organic ELlight emitting layer 1 will be described as an example of display devicein this embodiment according to the present invention. The displaydevice 10 in this embodiment is applicable to any flat panel displaydevice such as, for example, a liquid crystal display device, aself-light emitting display device, or an electronic paper-type displaydevice including an electrophoretic element or the like. For example,the display device 10 may be a liquid crystal display device includingthe substrate 7, a counter substrate facing the substrate 7, a liquidcrystal layer located between the substrate 7 and the counter substratefor each pixel 101, and a backlight unit that supplies light to theliquid crystal layer.

As shown in FIG. 2, the display device 10 in this embodiment accordingto the present invention may include, on a substrate 2 formed of a hardmaterial such as glass or the like, the organic EL light emitting layer1 that forms each pixel 101 included in the display unit 9. Although notshown in detail in FIG. 2, the organic EL light emitting layer 1 mayinclude, for example, a TFT driving circuit layer, a reflectiveelectrode, an organic EL layer, and a transparent electrode that arestacked in this order from the side of the substrate 2. The organic ELlayer may optionally include functional layers such as, for example, ahole injection layer, a hole transport layer, an electron transportlayer and an electron injection layer stacked in addition to the lightemitting layer.

The organic EL light emitting layer 1 is rapidly deteriorated when beingexposed to moisture, and therefore needs to be shielded against externalair. For this purpose, a surface of the organic EL light emitting layer1 is covered with a transparent sealing film 3 formed of, for example, asilicon nitride film formed by CVD or the like, and also is covered witha substrate 6 formed of a transparent hard material such as glass or thelike. Hereinafter, a structural body including the substrate 2 and alsothe organic EL light emitting layer 1 and the sealing film 3 formed onthe substrate 2 will be referred to as a “first substrate 7”, and asubstrate facing the first substrate 7 will be referred to as a “secondsubstrate 6”. The second substrate 6 may include a color filter orinclude, for example, a thin film device having a touch panel functionin accordance with the specifications of the display device 10.

As shown in FIG. 2, the display device 10 includes transparent resins 4and 5 such as, for example, an epoxy resin or the like between the firstsubstrate 7 and the second substrate 6. The resins 4 and 5 keep thedistance between the first substrate 7 and the second substrate 6, andthus keep the surface of the organic EL light emitting layer 1 and asurface of the second substrate 6 parallel to each other. The resins 4and 5 also have a role of preventing light reflection or refraction atthe surface of the organic EL light emitting layer 1 and the surface ofthe second substrate 6. Instead of the resins 4 and 5, a known membersuch as a sealing member or the like may be used to keep the distancebetween the first substrate 7 and the second substrate 6. In a structurein which the distance between the first substrate 7 and the secondsubstrate 6 is kept by the sealing member or the like, a gap may beprovided between the first substrate 7 and the second substrate 6. Thefirst substrate 7 and the second substrate 6 are joined together withsuch elements sandwiched therebetween, and thus the display device 10 isformed.

As shown in FIG. 3A, FIG. 3B and FIG. 3C, the display device 10 havingthe above-described structure includes the display unit 9 including theplurality of pixels 101 to display an image, and also includes aterminal unit 8 including a plurality of terminals TM that are used toprovide electric connection with the external circuit 103.

As shown in FIG. 3A, FIG. 3B and FIG. 3C, in the terminal unit 8, theplurality of terminals TM are exposed without being covered with any ofthe sealing film 3, the resins 4 and 5 and the second substrate 6 shownin FIG. 2. Ends of the plurality of terminals TM that are thus exposedare connected to, for example, the external circuit 103 (see FIG. 1)that supplies a driving signal. The plurality of terminals TM are alsoconnected to the thin film transistors and the like included in theorganic EL light emitting layer 1 via the lines, a driver circuit DR andthe like formed on the substrate 2. The driver circuit DR shown in FIG.3A, FIG. 3B and FIG. 3C correspond to the driver IC 102 in FIG. 1.

In the case where the sealing film 3 that covers the organic EL lightemitting layer 1 is provided on the entire surface of the substrate 2without being patterned in such a method of manufacturing the displaydevice 10, the plurality of terminals TM in the terminal unit 8 need tobe exposed from the sealing film 3. According to a known method forexposing the plurality of terminals TM, after the sealing film 3 isformed on the terminal unit 8, the sealing film 3 on the terminal unit 8is removed by tape-peeling or etching (dry etching or wet etching).

In order to prevent deterioration of the terminal unit 8, a protectivefilm formed of an inorganic insulating film such as a silicon nitridefilm or the like may be formed on the plurality of terminals TM and thelines. In the case where the protective film for the terminal unit 8 isformed of an inorganic insulating film, the protective film may possiblybe removed when the sealing film 3 on the terminal unit 8 is removed byetching because the sealing film 3 is also formed of an inorganicinsulating film.

In order to prevent this, a conventional display device does not includethe protective film on the plurality of terminals and the lines. Astructure of a terminal unit of such a conventional display device willbe described with reference to FIG. 10.

FIG. 10 is a cross-sectional view showing a schematic structure of theterminal unit of the conventional display device, and shows across-sectional structure of two terminals TM taken along linecorresponding to line A-A′ in FIG. 3C. The terminals TM are formed on afirst insulating film 19 that is formed on the substrate 2 so as to beinsulated from each other by a second insulating film 20. Namely, eachof the terminals TM is formed between two separate parts of the secondinsulating film 20. The first insulating film 19 and the secondinsulating film 20 may be formed of a silicon oxide film, a siliconnitride film or the like. Alternatively, the first insulating film 19and the second insulating film 20 may be formed of an insulating filmreferred to as an undercoat film or an interlayer insulating film thatis formed in a step of forming thin film transistors of the pixels 101.

The terminals TM and the lines connected to the terminals TM are formedas follows. First, protrusions (line patterns) 27 that are higher thanthe second insulating film 20 are formed of a metal material having alow resistance such as aluminum or the like. Then, a transparentconductive film 26 such as an ITO film or the like is formed so as tocover the protrusions 27. In this manner, the terminals TM and the linesincluding the protrusions 27 and the transparent conductive film 26 areformed. The sealing film 3 is formed on the terminals TM and the lines,namely, on a surface of the transparent conductive film 26. However, insuch a conventional display device including the terminals TM and thelines formed in this manner, when the sealing film 3 is removed, theprotrusions 27 formed of a metal material such as aluminum or the likemay possible be exposed from the transparent conductive film 26 formedon edges of the protrusions 27. When this occurs, the reliability of thedisplay device 10 is spoiled.

In order to prevent this, an organic insulating film may be used as aprotective film that protects the plurality of terminals TMs. Theorganic insulating film is formed of an organic material such as, forexample, an acrylic resin, polyimide or the like. However, such anorganic insulating film is difficult to be controlled in terms of thethickness, and may possibly provide a stepped portion between contactsurfaces of the terminals TM and the protective film. In addition, inthe case where an organic insulating film is used as the protective filmfor the terminals TM, the shape of conductive particles of ananisotropic conductive film (ACF) that is used for mounting the externalcircuit 103 may possibly be restricted to cause a mounting flaw,depending on the thickness of the organic insulating film.

In such a situation, the present inventor made studies on a method thatcan protect the plurality of terminals TM in the terminal unit 8 withoutinfluencing the mounting of the external circuit 103 or the like, andachieved the present invention.

Embodiment 1

Hereinafter, with reference to FIG. 4 through FIG. 6, a schematicstructure of a display device 10 in embodiment 1 according to thepresent invention will be described. FIG. 4 is a cross-sectional viewshowing a schematic structure of the display device 10 in embodiment 1according to the present invention. FIG. 5A and FIG. 5B show schematicstructures of the terminal unit 8 of the display device 10 in embodiment1 according to the present invention. FIG. 5A is a plan view of theterminal unit 8, and FIG. 5B is a cross-sectional view of the terminalunit 8. FIG. 6 is a cross-sectional view showing a schematic structureof a wiring unit of the display device 10 in embodiment 1 according tothe present invention.

In the following, an organic EL display device including an organic ELlight emitting layer 1 will be described as an example of display devicein this embodiment according to the present invention. The displaydevice 10 in this embodiment is applicable to any display device thatcontrols display gray scale of each of pixels by use of a thin filmtransistor. As described above, the display device 10 in this embodimentis applicable to any flat panel display device such as, for example, aliquid crystal display device, a self-light emitting display device, oran electronic paper-type display device including an electrophoreticelement or the like. Elements that are substantially the same as thoseof the elements described above with reference to FIG. 1 through FIG. 3Cwill bear the same reference signs therewith, and detailed descriptionsthereof will be omitted.

Among areas of the terminal unit 8 and areas of the display unit 9 ofthe display device 10 in embodiment 1 according to the presentinvention, FIG. 4 shows one area of the terminal unit 8 corresponding toone terminal and one area of the display unit 9 corresponding to onepixel 101. However, in actuality, the terminal unit 8 includes aplurality of terminals, and the display unit 9 includes a plurality ofpixels 101. As shown in FIG. 4, one area of the terminal unit 8corresponding to one pixel 101 includes a transistor unit 30 including athin film transistor, a capacitance unit 31 including a capacitanceelement that stores a voltage from a signal line 12, and a pixel unit 32that is a light emitting area of the pixel 101.

As shown in FIG. 4, on the substrate 2, the first insulating film 19including two insulating films 21 and 22 are formed. The insulatingfilms 21 and 22 are formed of a silicon oxide film, a silicon nitridefilm or the like below the thin film transistor. On the first insulatingfilm 19, a polycrystalline silicon layer 33, a gate insulating film 23,and a gate electrode layer 34 are formed. The polycrystalline siliconlayer 33 is partially doped with impurities, and a drain electrode and asource electrode are connected to the doped region, so that the thinfilm transistor is formed. On the thin film transistor, two insulatingfilms 24 and 25 are formed as inter-layer insulating films. Theinsulating films 24 and 25 are formed of a silicon oxide film, a siliconnitride film or the like. In a part of the terminal unit 8 and a part ofthe display unit 9, the gate insulating film 23 and the two insulatingfilms 24 and 25 form the second insulating film 20. In the structureshown in FIG. 4, the first insulating film 19 includes two layers andthe second insulating film 20 includes three layers. The presentinvention is not limited to such a structure. For example, the secondinsulating film 20 may include the insulating films 24 and 25 that areformed on the thin film transistor and does not need to include the gateinsulating film 23. In this case, the gate insulating film 23 is formedonly on the polycrystalline silicon layer 33.

In the second insulating film 20, a contact hole 50 that exposes atleast a part of the thin film transistor is formed. In the display unit9, the signal line 12 is formed on the second insulating film 20, andthe signal line 12 is connected to the thin film transistor via thecontact hole 50. The signal line 12 connected to the thin filmtransistor is covered with a third insulating film 13 that is formed ofan organic insulating film. On the third insulating film 13, a firstconductive film 14 connected to the signal line 12 via a contact holeformed in the third insulating film 13 is formed. On the firstconductive film 14, a fourth insulating film 15 is formed. On the fourthinsulating film 15, a reflective electrode 16 and a second conductivefilm 17 are formed. The first conductive film 14, the fourth insulatingfilm 15 and the second conductive film 17 form a capacitance elementconnected to the capacitance unit 31 in parallel. The first conductivefilm 14 is formed of a light-transmissive conductive film such as an ITOfilm or the like. The fourth insulating film 15 is formed of aninorganic film such as a silicon nitride film or the like. The secondconductive film 17 is formed of a light-transmissive conductive filmsuch as an ITO film or the like. The fourth insulating film 15 has anopening in at least the contact hole, and the first conductive film 14and the second conductive film 17 are connected to each other via theopening.

In an example of the pixel unit 32 shown in FIG. 4, the reflectiveelectrode 16 containing aluminum, silver or the like is located belowthe second conductive film 17 to form an anode electrode (positiveelectrode, reflective electrode) of the organic EL light emitting layer1. The present invention is not limited to such a structure. Althoughnot shown in FIG. 4, in actuality, an organic EL layer and a transparentelectrode (negative electrode) are formed on the second conductive film17 to form the organic EL light emitting layer 1. On the secondconductive film 17, a fifth insulating film 18 of an organic insulatingfilm is formed as a bank layer that demarcates the pixels 101.

In the meantime, in the terminal unit 8 shown in FIG. 4, a terminal line122 is formed on the second insulating film 20. The terminal line 122 iscovered with the third insulating film 13. A part of the thirdinsulating film 13 that is on the terminal line 122 is removed, and apart of the terminal line 122 is exposed from the third insulating film13. On the exposed part of the terminal line 122, the first conductivefilm 14 formed of a light-transmissive conductive film such as an ITOfilm or the like is formed so as to cover a part of the third insulatingfilm 13. As described above, the first conductive film 14 forms acapacitance element in the display unit 9. As can be seen, the terminalunit 8 includes the first conductive film 14 that forms the plurality ofterminals TM described above and shown in FIG. 3A, FIG. 3B and FIG. 3C.

Hereinafter, with reference to FIG. 5A, FIG. 5B and FIG. 6, steps formanufacturing the plurality of terminals TM and the lines in theterminal unit 8 will be described in detail.

FIG. 5B shows a cross-sectional structure of two terminals TM in theterminal unit 8 that is taken along a line corresponding to line A-A′ inFIG. 3B. FIG. 5A shows a planar structure of the two terminals TM shownin FIG. 5B. FIG. 6 shows a cross-sectional structure of two terminallines 122 in the wiring unit of the display device 10 that is takenalong a line corresponding to line B-B′ in FIG. 3C.

A substrate 11 shown in FIG. 5B and FIG. 6 corresponds to an assembly ofthe substrate 2 and the first insulating film 19 formed on the substrate2 shown in FIG. 4. In the terminal unit 8, the second insulating film 20is formed on the substrate 11 by use of the same material as that of theinterlayer insulating film as described above. A part of the secondinsulating film 20 formed on the substrate 11 that is enclosed by adashed line 20A in FIG. 5B is removed by a known method such as etchingor the like. As a result, an opening is formed where the terminal line122 is not located. This etching step performed on the second insulatingfilm 20 in the terminal unit 8 can be performed at the same time as anetching step performed on the interlayer insulating film (secondinsulating film 20) of the thin film transistor in the display unit 9.The two etching steps can be performed by use of one mask. In this step,in the display unit 9, the second insulating film 20 is etched at partson electrodes of the plurality of thin film transistors, so that aplurality of contact holes 50 are formed in the second insulating film20. Via the plurality of contact holes 50 thus formed in the secondinsulating film 20 allows a plurality of the signal lines 12 and theplurality of thin film transistors to be respectively connected to eachother in a connection step described below.

The shape of the opening that is formed by patterning and partiallyremoving the second insulating film 20 is not limited to the shapeenclosed by the dashed line 20A shown in FIG. 5B. In a latermanufacturing step, a solution is applied such that the third insulatingfilm 13 to be formed on the second insulating film 20 has a desiredthickness. The shape of the opening may be determined in accordance withthe amount of the solution. Depending on the amount of the solution usedto form the third insulating film 13, the second insulating film 20 inthe terminal unit 8 may have a part that is not removed even though theterminal line 122 is not formed on the part. As can be seen, the presentinvention is not limited to the structure shown in FIG. 5B.

Next, the signal line 12 and the terminal line 122 are formed of a metalmaterial such as aluminum or the like on the second insulating film 20.The signal line 12 and the terminal line 122 are formed by providing ametal film on the second insulating film 20 and patterning the metalfilm. In the display unit 9 and the terminal unit 8, the signal line 12and the terminal line 122 are formed at the same time by use of onemask. As a result of this step, as shown in FIG. 4, the signal line 12connected to the source/drain electrode of the thin film transistor viathe contact hole 50 in the second insulating film 20 is formed in thedisplay unit 9. As shown in FIG. 5B and FIG. 6, the terminal line 122 isformed on the second insulating film 20 in the terminal unit 8.

Next, the third insulating film 13 is formed on, and covers, the signalline 12 and the terminal line 122 is formed in the display unit 9 andthe terminal unit 8. The third insulating film 13 is formed of anorganic material such as an acrylic resin, polyimide or the like. Inthis step, in the terminal unit 8, the opening formed by removing thesecond insulating film 20 is filled with the organic material for thethird insulating film 13. The surface area of the opening in the secondinsulating film 20 (surface area of the part of the substrate 11 that isexposed by the opening) is optimized so that the third insulating film13 to be formed on the terminal line 122 can have a desired thickness.

It is now assumed that the third insulating film 13 to be formed on theterminal line 122 is a thin film having a thickness of 1 μm or less. Ifthe thickness of the third insulating film 13 is controlled only byfine-tuning the amount of the organic material without removing a partof the second insulating film 20, the thickness needs to be controlledat high precision, as compared with the method in this embodiment bywhich the second insulating film 20 is removed to expose a desiredsurface area of the substrate 11 and then the organic material isapplied to control the thickness of the insulating film 13. In thisembodiment, a part of the second insulating film 20 is removed inadvance, and this makes it easier to control the thickness of the thirdinsulating film 13. The step of removing a part of the second insulatingfilm 20 can be performed at the same time as the step of patterning theinterlayer insulating film (second insulating film 20) of the thin filmtransistor in the display unit 9. Therefore, the third insulating film13 having a desired thickness can be formed on the terminal line 122 ina simple manufacturing method with no need to significantly change anexisting manufacturing method.

As a result of such a step, the third insulating film 13 is formed as aprotective film that covers the terminal line 122. As shown in FIG. 5 B,the third insulating film 13 is partially removed by etching to form acontact hole (through-hole) that exposes the terminal line 122. On thepart of the terminal line 122 that is exposed by the contact hole, alight-transmissive conductive film such as an ITO film or the like isformed and patterned. Thus, the plurality of terminals TM are formed asparts of the first conductive film 14. A stepped portion is formed inthe first conductive film 14 between a surface of a part thereof that isin contact with the terminal line 122 and a surface of a part thereofthat is on the third insulating film 13. However, in this embodiment,such a stepped portion formed in the first conductive film 14 can have athickness of about 1 μm or less.

As can be seen, in this embodiment, the stepped portion formed in thefirst conductive film 14 that forms the terminals TM can be as thin asabout 1 μm or less. Because of this, the anisotropic conductive film(ACF) used to mount the external circuit 103 on the terminal unit 8 maybe of a type formed of small-diameter conductive particles. This candecrease the connection resistance of the terminal TM. This will bedescribed in more detail. If the stepped portion in the terminal TM isgreater than 1 μm, the conductive particles of the anisotropicconductive film (ACF) cannot be squashed properly, which may cause aflaw such as a line defect or the like. In order to avoid this, ananisotropic conductive film (ACF) formed of large-diameter conductiveparticles needs to be used. However, when such an anisotropic conductivefilm (ACF) formed of large-diameter conductive particles is used, theremay occur other problems that the line pitch cannot be made narrow andthat the number of particles per unit surface area is decreased toreduce the connection surface area, which raises the connectionresistance. In this embodiment, the thickness of the third insulatingfilm 13 is controlled such that the stepped portion formed in the firstconductive film 14 has a thickness of about 1 μm or less. This allows ananisotropic conductive film (ACF) formed of small-diameter conductiveparticles to be used, which decreases the connection resistance. Thus,generation of the mounting flaw can be prevented.

In this embodiment, the third insulating film 13 provided as aprotective film on the terminal TM and the terminal line 122 is formedof an organic material. Such a protective film formed of an organicmaterial has a high water resistance and thus prevents the terminal TMand the terminal line 122 from being corroded. This can improve theconnection reliability in the terminal unit 8.

As described above, in this embodiment, the terminals TM and theterminal lines 122 in the terminal unit 8 are protected by the thirdinsulating film 13 formed of an organic material, and the thirdinsulating film 13 can be formed to have a desired thickness. Therefore,the yield of mounting the external circuit 103 is not decreased, whichprovides a high reliability of the display device. Such a display devicecan be manufactured by a simple manufacturing method with no need tosignificantly change an existing manufacturing method.

Embodiment 2

Hereinafter, with reference to FIG. 7 through FIG. 9, a schematicstructure of a display device 40 in embodiment 2 according to thepresent invention will be described. FIG. 7 is a cross-sectional viewshowing a schematic structure of the display device 40 in embodiment 2according to the present invention. FIG. 8A and FIG. 8B show schematicstructures of the terminal unit 8 of the display device 40 in embodiment2 according to the present invention. FIG. 8A is a plan view of theterminal unit 8, and FIG. 8B is a cross-sectional view of the terminalunit 8. FIG. 9 is a cross-sectional view showing a schematic structureof the wiring unit of the display device 40 in embodiment 2 according tothe present invention.

Unlike the display device 10 in embodiment 1 according to the presentinvention, the display device 40 in embodiment 2 according to thepresent invention includes a protective film formed of an inorganicinsulating film below the third insulating film 13 formed of an organicinsulating film. Elements that are substantially the same as those ofthe elements in embodiment 1 described above with reference to FIG. 4through FIG. 6 will bear the same reference signs therewith, anddetailed descriptions thereof will be omitted.

As shown in FIG. 7, in the display device 40 in embodiment 2 accordingto the present invention, the first insulating film 19 and the secondinsulating film 20 are formed on a substrate 2, like in the display 10in embodiment 1 according to the present invention. In the terminal 8, apart of the second insulating film 20 that is enclosed by a dashed line20B in FIG. 8B, namely, a part of the second insulating film 20 wherethe terminal line 122 is not to be formed, is removed by a known methodsuch as etching or the like to form an opening, like in the displaydevice 10 in embodiment 1 according to the present invention. Thisetching step can be performed at the same time as the etching stepperformed on the interlayer insulating film (second insulating film 20)of the thin film transistor in the display unit 9.

After the metal film formed on the second insulating film 20 ispatterned to form the signal line 12 and the terminal line 122, thefourth insulating film 15 is formed of an inorganic insulating film soas to cover the second insulating film 20 as well as the signal line 12and the terminal line 122. In the display unit 9, the fourth insulatingfilm 15 forms a capacitance element of the capacitance unit 31, and isformed of an inorganic insulating film such as a silicon nitride film orthe like.

Next, the fourth insulating film 15 on the terminal line 122 ispartially removed by etching to expose the terminal line 122. On theexposed part of the terminal line 122, the second conductive film 17 isformed of a light-transmissive conductive film such as an ITO film orthe like and patterned. Thus, a plurality of terminals TM are formed.The second conductive film 17 is formed so as to cover the exposed partof the terminal line 122 and a part of a surface of the fourthinsulating film 15 that is in the vicinity thereof. The conductive film17 may be a layer that forms an anode electrode (positive electrode) ofthe organic EL light emitting layer 1.

On the fourth insulating film 15 and the second conductive film 17 thusformed, the fifth insulating film 18 is formed of an organic materialsuch as an acrylic resin, polyimide or the like. In the display unit 9,the fifth insulating film 18 acts as a bank layer that demarcates thepixels 101. In the terminal unit 8, the fifth insulating film 18 ispatterned so as to expose a part of the second conductive film 17, thepart acting as the terminal TM. Such a patterning performed on the fifthinsulating film 18 can be performed at the same time as the patterningfor forming the bank layer in the display unit 9.

In the terminal unit 8, the opening formed by removing a part of thesecond insulating film 20 (part enclosed by the dashed line 20B in FIG.8B is filled with the fifth insulating film 18. Therefore, in thisembodiment also, the surface area of the opening in the secondinsulating film 20 is optimized so that the fifth insulating film 18 tobe formed on the second conductive film 17 can have a desired thickness,like in the method of manufacturing the display device 10 inembodiment 1. Thus, the stepped portion formed between the part of thesecond conductive film 17 acting as the terminal TM and the fifthinsulating film 18 on the second conductive film 17 can be made thin soas not to influence the mounting of the external circuit 103, by asimple manufacturing method with no need to significantly changing anexisting manufacturing method.

In this embodiment, the fourth insulating film 15 formed of an inorganicinsulating film such as a silicon nitride film or the like protects theterminal line 122, and the fifth insulating film 18 formed of an organicinsulating film is provided on the fourth insulating film 15. Therefore,the display device manufactured in this embodiment has a high waterresistance, is prevented from being corroded, and has a higherreliability.

As described above, in embodiments 1 and 2 according to the presentinvention, the terminals TM and the terminal lines 122 in the terminalunit 8 are protected by the third insulating film 13 or the fifthinsulating film 18 each of which is formed of an organic insulatingfilm, and the third insulating film 13 and the fifth insulating film 18are formed to have a desired thickness. Therefore, the yield of mountingthe external circuit 103 is not decreased, which provides a highreliability of the display device. Such a display device can bemanufactured by a simple manufacturing method with no need tosignificantly change an existing manufacturing method.

The invention claimed is:
 1. A display device, comprising: a displayunit comprising a plurality of pixels respectively having thin filmtransistors; a terminal unit comprising an array of a plurality ofterminals, signals to control an operation of the thin film transistorsrespectively being input into the plurality of terminals; a firstinsulating film provided on a substrate, wherein the thin filmtransistors provided on the first insulating film; a second insulatingfilm provided in the display unit and in the terminal unit, and havingopenings located between the terminals; a plurality of signal linesprovided on the second insulating film and respectively connected to thethin film transistors; a plurality of terminal lines provided on thesecond insulating film in the terminal unit; and a third insulating filmlocated on the plurality of signal lines and the plurality of terminallines and formed of an organic insulating film, wherein each of theopenings exposes at least a part of the top surface of the firstinsulating film from the second insulating film between the terminals.2. The display device according to claim 1, wherein the plurality ofterminals are respectively connected to the plurality of terminal linesvia a plurality of contact holes provided in the third insulating film.3. The display device according to claim 1, wherein the plurality ofterminals are formed of a light-transmissive conductive film.
 4. Thedisplay device according to claim 1, wherein the third insulating filmcontains an acrylic resin or polyimide.
 5. A display device, comprising:a display unit comprising a plurality of pixels respectively having thinfilm transistors; a terminal unit comprising an array of a plurality ofterminals, signals to control an operation of the thin film transistorsrespectively being input into the plurality of terminals; a firstinsulating film provided on a substrate, wherein the thin filmtransistors are provided on the first insulating film; a secondinsulating film provided in the display unit and in the terminal unit,and having openings located between the terminals; a plurality of signallines provided on the second insulating film and respectively connectedto the thin film transistors; a plurality of terminal lines provided onthe second insulating film in the terminal unit; a third insulating filmlocated on the plurality of signal lines and formed of an organicinsulating film; a fourth insulating film formed from an inorganicinsulating film located on the third insulating film and the pluralityof terminal lines, having a plurality of contact holes each exposing apart of a corresponding terminal line among the plurality of terminallines, wherein the plurality of terminals provided on the fourthinsulating film and respectively connected to the plurality of terminallines via the plurality of contact holes; and a fifth insulating filmprovided on the plurality of terminals and exposing a part of each ofthe plurality of terminals, wherein each of the openings exposes atleast a part of the top surface of the first insulating film from thesecond insulating film between the terminals.
 6. The display deviceaccording to claim 5, wherein the plurality of terminals are formed of alight-transmissive conductive film.
 7. The display device according toclaim 5, wherein the third insulating film contains an acrylic resin orpolyimide.
 8. The display device according to claim 1, wherein the thirdinsulating film is formed so as to overlap the openings.
 9. The displaydevice according to claim 5, wherein the fourth insulating film and thefifth insulating film are formed so as to overlap the openings.